A diagnosis of acute bacterial sinusitis can be made when a child with an acute upper respiratory infection has symptoms lasting more than 10 days, or a severe onset of symptoms including fever and nasal discharge lasting at least three days in a row.

New in the 2013 guideline is a third scenario for diagnosis of acute bacterial sinusitis in a child with an upper respiratory infection with a worsening course of symptoms like nasal discharge, cough and fever after an initial improvement. In contrast to the 2001 guideline, which recommended antibiotic therapy for all children diagnosed with acute bacterial sinusitis, the 2013 guideline allows doctors to observe children with persistent illness lasting more than 10 days for an additional three days.

Children with severe onset or a worsening course of symptoms should receive antibiotics. First-line treatment is amoxicillin, which may be switched to another antibiotic if symptoms worsen or do not improve after 72 hours. The review of the evidence also indicates that imaging tests are not necessary in children with uncomplicated acute bacterial sinusitis, and thus they are not recommended by the AAP.